1. Field of the Invention
The present invention relates generally to an ice screw used in ice climbing and the like for securing a carabiner and the like to a body of ice.
2. Related Art
Extreme sports have become increasingly popular. An example of such an extreme sport includes winter, alpine or ice climbing. Ice climbing is similar to rock or cliff climbing, but includes the added challenge or obstacle of bodies of ice, such as frozen waterfalls, or snow packed cliffs. Thus, ice climbers seek out these conditions because of the added difficulty and challenge.
Ice climbing, like other types of climbing, requires special equipment. Some gear, such as an ice axe and crampons (special, spiked boot treads), assist the climber in grasping the surface or terrain being climbed. Other gear, such as rope, pitons (spikes), and carabiners, acts as safety or back-up systems to catch the climber if the need arises.
It will be appreciated that a climber, suspended hundreds of feet in the air on a slab of ice, has certain expectations and requirements for climbing equipment. For example, it is critical that the gear be strong enough to hold the weight of the climber, dynamic loading of a falling climber, capable of being attached to and holding the climbing surface (holding power), light enough to be carried, and quickly and easily utilized. A climber does not want to carry any more equipment than is necessary, or equipment that is difficult to use.
Initially, much of the gear used in winter, alpine, or ice climbs was the same gear used in rock climbing. For example, rock pitons would be driven into the ice, just as they had been driven into cracks in the rock. Some modifications were made to the rock piton to improve performance on the ice, such as the addition of teeth, a U-shaped shaft, and a hollow tube. Hammering these devices into the ice, however, was inherently dangerous as the hammering could shatter the ice and compromise its integrity. A corkscrew type device was developed that could be twisted into the ice without as much danger of fracturing the ice, but it had little shear strength. The most popular design has been the modem, twist-in, tubular design, or ice screw. The twist-in tube does not fracture the ice as much as the hammered-in piton type, and has greater strength than the corkscrews.
Typically, an ice screw is a hollow shaft having an external screw thread. One end has sharp teeth for piercing the ice, and the other end has a head or rim. A hanger is attached to the shaft at the head, and has an opening or eye for clipping on a carabiner. The hanger can be secured to the shaft such that they turn together, and the hanger can be used to turn or screw the shaft into the ice. The climber typically forces the toothed end of the ice screw into the ice, and screws it into the ice using the hanger as a lever arm. A rope, secured to the climber, can be passed through the carabiner to secure the climber to the ice screw, and thus to the ice. Handles have been developed, that attach to the screw or hanger, to facilitate screwing the shaft into the ice.
It also will be appreciated that turning or screwing the shaft into the ice can be a difficult job due to friction between the ice and the screw. The further the shaft is inserted into the ice, the more difficult it can be to turn. It has been proposed to provide the shaft of these screws with a constant or linear reverse taper from the toothed end to the head, so that the toothed end has a larger diameter than the head. The larger diameter of the toothed end creates a larger hole in the ice to reduce the friction with the rest of the shaft. In reality, however, it is difficult and expansive to provide such a taper on an ice screw. Special machines and extra effort are required to obtain such a taper. In addition, it is often difficult to ascertain whether or not the screw even has a taper.
It has been recognized that it would be advantageous to develop an ice screw that is easier and faster to use.
The invention provides an ice screw device with at least one screw thread formed on a tubular shank or shaft. The tubular shank includes an ice engaging portion to be introduced into ice, a distal tip, and a proximal head portion. A hanger can be coupled to the head portion of the shank to allow climbing equipment, such as a carabiner, to be coupled to the tubular shank. In addition, the ice engaging portion of the tubular shank can include a reverse taper.
In accordance with another more detailed aspect of the present invention, the ice screw device advantageously includes a majority of the reverse taper of the ice engaging portion being located proximate the tip and within less than half a length of the ice engaging portion. Thus, a majority of the reverse taper can be located within the first two inches of the ice engaging portion of the tubular shank. It has been found that such a configuration of the ice engaging portion is faster and easier to insert into the ice. In addition, it is believed that concentrating a majority of the taper in a smaller section or length also provides a taper that is more visible, thus making the taper easier to visually verify by the climber. In addition, it is believed that providing a more visible taper provides a marketing benefit because the climber is able to see the taper at the point of purchase.
In accordance with another more detailed aspect of the present invention, the ice engaging portion of the ice screw device advantageously includes a non-linear, varying, or non-constant taper. The ice engaging portion can include at least two sections having different tapers. In one aspect, a first section nearer the tip can have first taper, or first reverse taper, greater than a second taper, or second reverse taper, of a second section nearer the head portion. Again, it has been found that such a configuration is easier to insert into the ice.
Additional features and advantages of the invention will be apparent from the detailed description which follows, taken in conjunction with the accompanying drawings, which together illustrate, by way of example, features of the invention.